FWIW, the Astros were on 92.5/93.3 FM in San Antonio this Sunday. They are normally on 760 AM. My guess is that they will typically be on 760 AM, but will be bumped back to 92.5/93.3 FM when 760 wants to broadcast crap like WNBA, minor league hockey, etc. This is better than years past, since they weren't (to the best of my knowledge) playing the Astros on other stations until this year.
As for Sirius XM, I have it, but I'm chasing my kids around most nights, so radio is typically more convenient. We should probably complain to the Astros about the sad state of affiliates. Now that they're world champs, maybe they'll listen.
Or maybe the right way to do this is to bug your local sports station? I have no idea, but I'm happy to help Twitter-shame radio stations on anyone's behalf if it will help you get a decent affiliate in your area!